1. Technical Field of the Invention
The present invention relates to novel s-triazine compounds bearing two substituents selected from among hindered para-aminobenzalmalonate and para-aminobenzalmalonamide groups and an aminobenzoate or aminobenzamide substituent and to their applications in cosmetics as sunscreen agents active in the region of UV radiation.
The present invention also relates to photoprotective compositions comprising such novel s-triazine compounds as sunscreen agents active in the region of UV radiation.
2. Description of Background and/or Related and/or Prior Art
It is known that radiation with wavelengths of from 280 nm to 400 nm makes possible browning of the human epidermis and that radiation with wavelengths of from 280 to 320 nm, known under the name of UV-B radiation, causes erythemas and skin burns which may be harmful to the development of natural tanning.
It is also known that UV-A rays, with wavelengths of from 320 to 400 nm, which cause browning of the skin, are capable of bringing about a detrimental change in the latter, in particular in the case of sensitive skin and/or of skin continually exposed to solar radiation. UV-A rays bring about in particular a loss of elasticity of the skin and the appearance of wrinkles, resulting in premature cutaneous aging. They promote the triggering of the erythemal reaction or accentuate this reaction in certain individuals and can even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, such as the retention of the natural elasticity of the skin, individuals increasingly desire to control the effect of UV-A radiation on their skin. The term “sun protection factor” is understood to mean the ratio of the irradiation time necessary to reach the erythemogenic threshold in the presence of the screening agent tested to the irradiation time necessary to reach the same threshold in the absence of screening agent.
It is therefore desirable to have available compounds capable of absorbing the entire range of UV radiation, both UV-B and UV-A rays.
In addition to their power in screening out UV-B and UV-A radiation, the desired photoprotective compounds must also exhibit good cosmetic properties, good solubility in conventional solvents and in particular in fatty substances, such as oils and fats, and good resistance to water and to perspiration (persistence) and very good photostability.
Mention may in particular be made, among all of the compounds which have been recommended for this purpose, of the s-triazine derivatives carrying para-aminobenzalmalonate substituents disclosed in EP-0,507,691 and EP-0,841,341, assigned to the assignee hereof. However, these compounds possess a photochemical stability and a solubility in conventional solvents which are not yet entirely satisfactory.